usr/src/lib/libwrap/percent_x.c

   1 /*
   2  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 #pragma ident   "%Z%%M% %I%     %E% SMI"
   7
   8  /*
   9   * percent_x() takes a string and performs %<char> expansions. It aborts the
  10   * program when the expansion would overflow the output buffer. The result
  11   * of %<char> expansion may be passed on to a shell process. For this
  12   * reason, characters with a special meaning to shells are replaced by
  13   * underscores.
  14   *
  15   * Diagnostics are reported through syslog(3).
  16   *
  17   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
  18   */
  19
  20 #ifndef lint
  21 static char sccsid[] = "@(#) percent_x.c 1.4 94/12/28 17:42:37";
  22 #endif
  23
  24 /* System libraries. */
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <unistd.h>
  29 #include <syslog.h>
  30 #include <string.h>
  31
  32 extern void exit();
  33
  34 /* Local stuff. */
  35
  36 #include "tcpd.h"
  37
  38 /* percent_x - do %<char> expansion, abort if result buffer is too small */
  39
  40 char   *percent_x(result, result_len, string, request)
  41 char   *result;
  42 int     result_len;
  43 char   *string;
  44 struct request_info *request;
  45 {
  46     char   *bp = result;
  47     char   *end = result + result_len - 1;      /* end of result buffer */
  48     char   *expansion;
  49     int     expansion_len;
  50     static char ok_chars[] = "1234567890!@%-_=+:,./\
  51 abcdefghijklmnopqrstuvwxyz\
  52 ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  53     char   *str = string;
  54     char   *cp;
  55     int     ch;
  56
  57     /*
  58      * Warning: we may be called from a child process or after pattern
  59      * matching, so we cannot use clean_exit() or tcpd_jump().
  60      */
  61
  62     while (*str) {
  63         if (*str == '%' && (ch = str[1]) != 0) {
  64             str += 2;
  65             expansion =
  66                 ch == 'a' ? eval_hostaddr(request->client) :
  67                 ch == 'A' ? eval_hostaddr(request->server) :
  68                 ch == 'c' ? eval_client(request) :
  69                 ch == 'd' ? eval_daemon(request) :
  70                 ch == 'h' ? eval_hostinfo(request->client) :
  71                 ch == 'H' ? eval_hostinfo(request->server) :
  72                 ch == 'n' ? eval_hostname(request->client) :
  73                 ch == 'N' ? eval_hostname(request->server) :
  74                 ch == 'p' ? eval_pid(request) :
  75                 ch == 's' ? eval_server(request) :
  76                 ch == 'u' ? eval_user(request) :
  77                 ch == '%' ? "%" : (tcpd_warn("unrecognized %%%c", ch), "");
  78             for (cp = expansion; *(cp += strspn(cp, ok_chars)); /* */ )
  79                 *cp = '_';
  80             expansion_len = cp - expansion;
  81         } else {
  82             expansion = str++;
  83             expansion_len = 1;
  84         }
  85         if (bp + expansion_len >= end) {
  86             tcpd_warn("percent_x: expansion too long: %.30s...", result);
  87             sleep(5);
  88             exit(0);
  89         }
  90         memcpy(bp, expansion, expansion_len);
  91         bp += expansion_len;
  92     }
  93     *bp = 0;
  94     return (result);
  95 }